1. Field of the Disclosure
The disclosure relates generally to retractable instruments and more specifically to cap-less, retractable writing instruments having a one-piece valve door actuating assembly.
2. Related Technology
One example of a cap-less, retractable writing instrument is shown in U.S. Pat. No. 5,048,990, which is hereby incorporated by reference. The cap-less writing instrument includes a writing member having a writing tip. The writing member is accommodated in a valve that is disposed inside a writing instrument body. A lid for closing an end opening of the valve is disposed on the valve near the front end thereof. A writing member moving mechanism moves the writing member forwardly and locks the writing member at a writing position with the writing tip protruding through the front of the writing instrument body. The moving mechanism includes separate flexible thread-like members that connect the writing member moving mechanism to the lid so that after the writing member is retracted, the lid is pulled backwardly so as to be brought into contact with the valve, thereby substantially sealing the writing member within the valve and preventing the writing tip from drying out. Because the prior art cap-less writing instrument uses flexible connecting members, the prior art cap-less writing instrument relies to some extent on the nib to push the lid to an open position during extension of the writing instrument at least until the lid is positioned such that the thread member can exert a backwardly directed force on same. As a result of this repeated contact between the nib and the lid, ink builds up on the inner surface of the lid. The uneven inner lid surface results in incomplete contact with the valve. This incomplete contact manifests as one or more breaches in the seal between the lid the valve, thereby allowing premature ink or solvent evaporation from the writing tip and lending to diminished performance of the entire assembly.
Some capless writing instruments incorporate more robust connecting members. One such writing instrument includes connecting members which are molded into a snap ring or seal seat and thus connect the snap ring to the lid. One example of a prior capless writing instrument is the Pentel NX50, which is currently available in Japan. However, in such writing instruments, the lid is a separate component from the valve body. Because the lid is separate component, such prior capless writing instruments use a complicated set of channels and tabs on the connecting members and/or the valve body to bias the lid open when protracting the writing instrument. During closing, it is easy for alignment between the lid and the valve to become displaced and for the lid to contact the valve in different orientations due to the separate components (i.e., there is no alignment mechanism between the lid and valve). As a result, over time, the lid can become worn and deformed and ultimately lose the ability to reliably seal the valve, thus leading to ink evaporation and premature drying of the nib.